The present invention relates to nuclear sensors for sensing gamma rays, and more specifically to a signal processing circuit for a gamma ray sensor that provides improved performance and simplified calibration.
Conventional gamma ray sensors utilize signal processing and energy calibration. The calibration of these devices typically requires a radiation source that is regulated by the Department of Transportation (DOT), and DOT considers these radiation sources as hazardous. An example of such a sensor is a high-purity germanium detector. Such detectors, however, require in-field calibration with radiation sources to ensure accurate readings. This calibration is extremely cumbersome and relatively dangerous, and it frequently requires governmental licensing. Moreover, high-purity germanium detectors must be cooled to liquid-nitrogen temperatures, and they are relatively fragile. These detectors are relatively bulky, they have difficulty operating over a wide temperature range, and they require relatively high power sources.
U.S. Pat. No. 6,781,134 discloses a handheld cadmium zinc telluride (CZT) radiation detector. The portable radiation detector implements a fuzzy-logic radioisotope identification procedure adapted for in-field analysis. The handheld CZT radiation detector includes a coplanar grid CZT gamma ray sensor. Unlike high-purity germanium detectors, the CZT radiation detector does not require in-field calibration or cooling to liquid-nitrogen temperatures. The CZT detector, however, is temperature sensitive, and it cannot operate over a wide temperature range.
There is a need for an easily calibrated nuclear sensor with a nuclear sensor signal processing circuit that is capable of operating over a relatively wide temperature range for use in a nuclear sensor that is both compact and uses relatively low power sources.